(12-04-2013, 05:27 PM)ScrapMetal Wrote: I completely dis-assembled the chuck. On the Jacobs ball-bearing chucks the process is fairly simple. This is from Jacobs site:

http://www.jacobschuck.com/drill-chuck-repair.asp

Quote:Drill Chuck Repair / Dissassembly
Drill Chuck Support

This drill chuck repair guide outlines the methods of drill chuck repair for the various plain and ball bearing keyed drill chucks. This drill chuck repair guide is also available as a pdf document.
Keyed Drill Chuck Disassembly
Plain Bearing drill chucks:

Extend the jaws to half capacity, press the sleeve off over front (jaw end) of body, remove the nut halves. (illus. E).
Ball bearing drill chucks:

Extend the jaws to half capacity, press the sleeve off over front (jaw end) of body, remove the nut halves, jaws, bearing race. and thrust washer (illus. E).
Illus. E. - Drill Chuck Disassembly



Keyed Drill Chuck Assembly

CAUTION: Each of the three Jaws differ slightly from the other by the location of the threaded portion (illus. G). In order to ensure proper operation, they must be re-installed in the proper sequence.
Plain Bearing drill chucks:

Refer to illus. C and Insert the jaws in the correct sequence when viewing the chuck from the body nose diameter. Insert No. 1 jaw (with small step) first, then No. 2 jaw (With largest step) in the clockwise position, then No 3 jaw (without a step) should be inserted.

Turn chuck jaws to closed position and check to ensure that all three jaws are properly aligned. The height of all three jaws should be uniform.

A good grade of grease should be applied to the jaw and nut threads, then the nut halves should be closed around the jaws Extend jaws to half capacity. Press on the sleeve with an arbor press (illus. F).
Illus. F. - Drill Chuck Assembly



Ball bearing drill chucks:

Slip the thrust race over jaw end of the body until it contacts the rear flange. Slip the caged bearing over jaw end of the body until it contacts the thrust race.

Follow Plain Bearing jaw assembly and nut procedure.

JAW NUMBER INDICATED BY PROFILES SHOWN BELOW.



Illus. G. - Drill Jaw Number

Following directions I used my 12-ton hydraulic press to remove the outer shell. The innards are about as simple as can be. There is a lower bearing race that is a one piece "ring" and the upper bearing race which is split in half that also contains the threads for actuating the jaws.

The two hardest things are to keep track of the ball bearings and to figure out which jaws are which (1, 2, or 3). The diagram is helpful but the jaws never seem to look quite like the drawings.

In this case I didn't even bother to remove the arbor. Once I was done rebuilding the chuck (and the whole mess had been through a couple of baths) I just spent some quality time with some oil, a tap, and some paper towels to twist down into the threaded hole and remove excess "crap".

If necessary you can buy "rebuild" kits for Jacobs chucks (http://www.use-enco.com) that I have gotten for other chuck rebuilds but this one really didn't need it. Cleaning out the reddish-brown "glue" was all that was necessary to turn it back in to a smoothly working chuck.

-Ron